19-4815; Rev 3; 3/11
KIT
ATION
EVALU
BLE
AVAILA
Low-Cost, 3A, 4.5V to 28V Input, 350kHz, PWM
Step-Down DC-DC Regulator with Internal Switches
General Description
The MAX15041 low-cost, synchronous DC-DC convert-
er with internal switches delivers an output current up to
3A. The MAX15041 operates from an input voltage of
4.5V to 28V and provides an adjustable output voltage
from 0.6V to 90% of V
IN
, set with two external resistors.
The MAX15041 is ideal for distributed power systems,
preregulation, set-top boxes, television, and other con-
sumer applications.
The MAX15041 features a peak-current-mode PWM con-
troller with internally fixed 350kHz switching frequency
and a 90% maximum duty cycle. The current-mode con-
trol architecture simplifies compensation design, and
ensures a cycle-by-cycle current limit and fast response
to line and load transients. A high-gain transconductance
error amplifier allows flexibility in setting the external com-
pensation by using a type II compensation scheme,
thereby allowing the use of all ceramic capacitors.
This synchronous buck regulator features internal
MOSFETs that provide better efficiency than asynchro-
nous solutions, while simplifying the design relative to
discrete controller solutions. In addition to simplifying
the design, the integrated MOSFETs minimize EMI,
reduce board space, and provide higher reliability by
minimizing the number of external components.
The MAX15041 also features thermal shutdown and
overcurrent protection (high-side sourcing and low-side
sinking), and an internal 5V LDO with undervoltage
lockout. In addition, this device ensures safe startup
when powering into a prebiased output.
Other features include an externally adjustable soft-start
that gradually ramps up the output voltage and reduces
inrush current. Independent enable control and power-
good signals allow for flexible power sequencing.
The MAX15041 is available in a space-saving, high-
power, 3mm x 3mm, 16-pin TQFN-EP package and is
fully specified from -40°C to +85°C.
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Features
Up to 3A of Continuous Output Current
±1% Output Accuracy Over Temperature
4.5V to 28V Input Voltage Range
Adjustable Output Voltage Range from 0.606V to
0.9 x V
IN
Internal 170mΩ R
DS-ON
High-Side and 105mΩ
R
DS-ON
Low-Side Power Switches
Fixed 350kHz Switching Frequency
Up to 93% Efficiency
Cycle-By-Cycle Overcurrent Protection
Programmable Soft-Start
Stable with Low-ESR Ceramic Output Capacitors
Safe Startup into Prebiased Output
Enable Input and Power-Good Output
Fully Protected Against Overcurrent and
Overtemperature
V
DD
LDO Undervoltage Lockout
Space-Saving, Thermally Enhanced, 3mm x 3mm
Package
MAX15041
Ordering Information
PART
MAX15041ETE+
TEMP RANGE
PIN-
PACKAGE
TOP
MARK
AGV
-40°C to +85°C 16 TQFN-EP*
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Typical Operating Circuit
INPUT
12V
IN
EN
MAX15041
V
DD
PGND
PGOOD
PGOOD
SS
SGND
FB
COMP
LX
BST
OUTPUT
1.8V AT 3A
Applications
Distributed Power Systems
Wall Adapters
Preregulators
Set-Top Boxes
Televisions
xDSL Modems
Consumer Products
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Low-Cost, 3A, 4.5V to 28V Input, 350kHz, PWM
Step-Down DC-DC Regulator with Internal Switches
MAX15041
ABSOLUTE MAXIMUM RATINGS
IN to SGND.............................................................-0.3V to +30V
EN to SGND .................................................-0.3V to (V
IN
+ 0.3V)
LX to PGND ................................-0.3V to min (+30V, V
IN
+ 0.3V)
LX to PGND .....................-1V to min (+30V, V
IN
+ 0.3V) for 50ns
PGOOD to SGND .....................................................-0.3V to +6V
V
DD
to SGND............................................................-0.3V to +6V
COMP, FB, SS to SGND..............-0.3V to min (+6V, V
DD
+ 0.3V)
BST to LX .................................................................-0.3V to +6V
BST to SGND .........................................................-0.3V to +36V
SGND to PGND ....................................................-0.3V to +0.3V
LX Current (Note 1) ....................................................-5A to +8A
Converter Output Short-Circuit Duration ...................Continuous
Continuous Power Dissipation (T
A
= +70°C)
16-Pin TQFN (derate 14.7mW/°C above +70°C)
Multilayer Board .........................................................1666mW
Operating Temperature Range ..........................-40°C to +85°C
Junction Temperature .....................................................+150°C
Storage Temperature Range ............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
Note 1:
LX has internal clamp diodes to PGND and IN. Applications that forward bias these diodes should take care not to exceed
the IC’s package power dissipation.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
PACKAGE THERMAL CHARACTERISTICS (Note 2)
16 TQFN-EP
Junction-to-Ambient Thermal Resistance (
θ
JA
).........+48°C/W
Junction-to-Case Thermal Resistance (
θ
JC
) ...............+7°C/W
Note 2:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to
www.maxim-ic.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(V
IN
= 12V, C
VDD
= 1µF, C
IN
= 22µF, T
A
= T
J
= -40°C to +85°C, typical values are at T
A
= +25°C, unless otherwise noted.) (Note 3)
PARAMETER
STEP-DOWN CONVERTER
Input-Voltage Range
Quiescent Current
Shutdown Input Supply Current
ENABLE INPUT
EN Shutdown Threshold Voltage
EN Shutdown Voltage Hysteresis
EN Lockout Threshold Voltage
EN Input Current
POWER-GOOD OUTPUT
PGOOD Threshold
PGOOD Threshold Hysteresis
PGOOD Output Low Voltage
PGOOD Leakage Current
ERROR AMPLIFIER
Error Amplifier
Transconductance
Error Amplifier Voltage Gain
FB Set-Point Accuracy
g
MV
A
VEA
V
FB
600
1.6
90
606
612
mS
dB
mV
V
PGOOD_TH
V
PGOOD_HYST
V
PGOOD_OL
I
PGOOD
I
PGOOD
= 5mA, V
FB
= 0.5V
V
PGOOD
= 5V, V
FB
= 0.7V
V
FB
rising
540
560
15
35
10
100
584
mV
mV
mV
nA
V
EN_SHDN
V
EN_HYST
V
EN_LOCK
V
EN_LOCK_HYST
I
EN
V
EN
= 2.9V
2
V
EN
rising
1.7
V
EN
rising
1.4
100
1.95
100
5.3
9
2.15
V
mV
V
mV
µA
V
IN
I
IN
Not switching
V
EN
= 0V, V
DD
regulated by internal
LDO
V
EN
= 0V, V
IN
= V
DD
= 5V
4.5
2.1
2
18
28
4
12
28
V
mA
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Low-Cost, 3A, 4.5V to 28V Input, 350kHz, PWM
Step-Down DC-DC Regulator with Internal Switches
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 12V, C
VDD
= 1µF, C
IN
= 22µF, T
A
= T
J
= -40°C to +85°C, typical values are at T
A
= +25°C, unless otherwise noted.) (Note 3)
PARAMETER
FB Input Bias Current
SS Current
SS Discharge Resistance
SS Prebiased Mode Stop Voltage
Current Sense to COMP
Transconductance
COMP Clamp Low
PWM Compensation Ramp Valley
PWM CLOCK
Switching Frequency
Maximum Duty Cycle
Minimum Controllable On-Time
INTERNAL LDO OUTPUT (V
DD
)
V
DD
Output Voltage
V
DD
Short-Circuit Current
LDO Dropout Voltage
V
DD
Undervoltage Lockout
Threshold
V
DD
Undervoltage Lockout
Hysteresis
POWER SWITCH
LX On-Resistance
High-Side Switch Source
Current-Limit Threshold
Low-Side Switch Sink
Current-Limit Threshold
LX Leakage Current
BST Leakage Current
THERMAL SHUTDOWN
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
HICCUP PROTECTION
Blanking Time
16 x Soft-
Start Time
Rising
+155
20
°C
°C
V
BST
= 33V, V
IN
= V
LX
= 28V
V
BST
= 5V, V
IN
= 28V, V
LX
= 0V
V
BST
= 33V, V
IN
= V
LX
= 28V
High-side switch, I
LX
= 1A
Low-side switch, I
LX
= 1A
5
170
105
6
-3
10
10
10
305
175
7.2
mΩ
A
A
nA
nA
V
UVLO_TH
V
UVLO_HYST
V
DD
I
VDD
= 1mA to 25mA, V
IN
= 6.5V
V
IN
= 6.5V
I
VDD
= 25mA, V
DD
drops by -2%
V
DD
rising
4.75
30
5.1
80
250
4
150
600
4.25
5.5
V
mA
mV
V
mV
f
SW
D
315
350
90
150
385
kHz
%
ns
G
MOD
V
FB
= 0.7V
SYMBOL
I
FB
I
SS
R
SS
V
FB
= 0.5V
V
FB
= 0.7V
V
SS
= 0.45V, sourcing
I
SS
= 10mA, sinking, V
EN
= 1.6V
CONDITIONS
MIN
-100
-100
4.5
5
6
0.65
9
0.68
830
TYP
MAX
+100
+100
5.5
UNITS
nA
µA
Ω
V
S
V
mV
MAX15041
Note 3:
Specifications are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by
design and characterization.
_______________________________________________________________________________________
3
Low-Cost, 3A, 4.5V to 28V Input, 350kHz, PWM
Step-Down DC-DC Regulator with Internal Switches
MAX15041
Typical Operating Characteristics
(V
IN
= 12V, V
OUT
= 3.3V, C
VDD
= 1µF, C
IN
= 22µF, T
A
= +25°C, circuit of Figure 3 (see Table 1 for values), unless otherwise specified.)
EFFICIENCY vs. LOAD CURRENT
MAX15041 toc01
EFFICIENCY vs. LOAD CURRENT
MAX15041 toc02
OUTPUT-VOLTAGE REGULATION
vs. LOAD CURRENT
OUTPUT-VOLTAGE REGULATION (%)
MAX15041 toc03
100
95
90
EFFICIENCY (%)
85
80
75
70
65
60
55
50
0
0.5
1.0
1.5
2.0
2.5
V
OUT
= 5.0V
V
OUT
= 3.3V
V
OUT
= 2.5V
V
OUT
= 1.8V
V
OUT
= 1.2V
V
IN
= 12V
100
95
90
EFFICIENCY (%)
85
80
75
70
65
60
55
50
V
OUT
= 3.3V
V
OUT
= 2.5V
V
OUT
= 1.8V
V
OUT
= 1.2V
0
0.5
1.0
1.5
2.0
2.5
V
IN
= 5V
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
3.0
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
LOAD CURRENT (A)
LOAD CURRENT (A)
LOAD CURRENT (A)
LOAD-TRANSIENT WAVEFORMS
MAX15041 toc04
NORMALIZED OUTPUT VOLTAGE
vs. TEMPERATURE
MAX15041 toc05
NORMALIZED OUTPUT VOLTAGE
vs. TEMPERATURE
I
LOAD
= 2A
NORMALIZED OUTPUT VOLTAGE
1.002
1.000
0.998
0.996
0.994
0.992
MAX15041 toc06
1.002
I
LOAD
= 0A
NORMALIZED OUTPUT VOLTAGE
1.001
1.000
0.999
0.998
0.997
0.996
0.995
1.004
I
LOAD
2A/div
V
OUT
AC-COUPLED
200mV/div
V
PGOOD
5V/div
200µs/div
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (NC)
TEMPERATURE (NC)
FB SET POINT vs.TEMPERATURE
MAX15041 toc07
SWITCHING FREQUENCY
vs. INPUT VOLTAGE
MAX15041 toc08
610
385
375
FREQUENCY (kHz)
365
355
345
335
T
A
= +85NC
T
A
= +25NC
T
A
= -40NC
325
608
FB SET POINT (mV)
606
604
602
600
-40
-15
10
35
60
85
TEMPERATURE (NC)
315
0
5
10
15
20
25
INPUT VOLTAGE (V)
4
_______________________________________________________________________________________
Low-Cost, 3A, 4.5V to 28V Input, 350kHz, PWM
Step-Down DC-DC Regulator with Internal Switches
Typical Operating Characteristics (continued)
(V
IN
= 12V, V
OUT
= 3.3V, C
VDD
= 1µF, C
IN
= 22µF, T
A
= +25°C, circuit of Figure 3 (see Table 1 for values), unless otherwise specified.)
MAX15041
INPUT SUPPLY CURRENT
vs. INPUT VOLTAGE
L = 4.7FH
I
LOAD
= 0A
MAX15041 toc09
SHUTDOWN CURRENT
vs. INPUT VOLTAGE
9
SHUTDOWN CURRENT (FA)
8
7
6
5
4
3
2
1
MAX15041 toc10
SHUTDOWN CURRENT
vs. TEMPERATURE
MAX15041 toc11
16
INPUT SUPPLY CURRENT (mA)
15
14
13
12
11
10
0
5
10
15
20
25
INPUT VOLTAGE (V)
10
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0
0
5
10
15
20
25
INPUT VOLTAGE (V)
SHUTDOWN CURRENT (FA)
-40
-15
10
35
60
85
TEMPERATURE (NC)
SHUTDOWN WAVEFORMS
MAX15041 toc12
OUTPUT SHORT-CIRCUIT WAVEFORMS
MAX15041 toc13
V
EN
5V/div
V
OUT
2V/div
I
L
2A/div
V
PGOOD
5V/div
V
OUT
2V/div
I
IN
5A/div
I
L
5A/div
V
SS
2V/div
100µs/div
10ms/div
SWITCHING WAVEFORMS
MAX15041 toc14
SOFT-START WAVEFORMS
MAX15041 toc15
V
LX
10V/div
V
EN
5V/div
V
OUT
2V/div
I
L
2A/div
V
OUT
AC-COUPLED
50mV/div
1µs/div
400µs/div
I
L
2A/div
V
PGOOD
5V/div
_______________________________________________________________________________________
5
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